This invention relates for apparatus for applying a foam to a moving web in general, and more particularly an improved apparatus of this nature which has better control over the amount of foam applied to the web.
Apparatus for applying foam to a moving web which includes a foam generator and a foam box which is coupled to th foam generator, the foam box being arranged transversely to the web, extending over its width and having on its underside, an opening which extends over the width of the web, and under which a rotatable cylinder is arranged which extends over the width of the web, the cylinder being sealed against the foam box except for an exit for the foam, with the cylinder, in its rotation, carrying foam along at its surface, from the foam box and depositing it on the web passing underneath the cylinder, is described in German Offenlegungsschrift No. 26 31 340.
In the known design, the objective is the manufacture of fibrous fabrics which are impregnated with an aqueous binder. Above the cylinder, a funnel-like chargeing box is arranged, the walls of which extend approximately radially to the cylinder. The foam which rests in the charging box on the cylinder is carried along at the surface of the cylinder under the wall which is in front during rotation, and is transferred by the cylinder to the web of material which passes underneath it. At the front edge of the charging box, a strip-like wiper blade is provided for adjusting the gap which determines the layer thickness of the foam carried along by the cylinder. In impregnating a fiber fabric with a binder, great uniformity of the foam application is not important. It therefore does not matter if the foam carried along at the surface of the cylinder sometimes is not completely uniform, or if a bulge is formed on the entrance side between the cylinder and the web. In foam dyeing, however, these phenomena are not permissible, since even small differences in the amount of liquid applied result in differences in the depth of the hue, which are distinctly visible in the finished product and can be tolerated in no way if the dyed material is, for instance, lengths of rugs to be used as display material.